My task is to create a program to open and close an electronic valve that is plugged into GPIO ports on my BeagleBone, by using TTL signals.
Questions:
Can I do this?
How do I make an executable file to do this?
Can someone refer me to documentation on this?
Am I going about this in the wrong way?
Thank you.
P.S. If you couldn't already tell I am very new to this.
Yes
There are many ways. It's actually a pretty standard Linux computer and you can use any of a "million" different programming languages to achieve this. This also means you don't have to look for "Beaglebone" specific instructions (beyond the GPIO info below), but your problem is just "How do I write a program that can write text to a file on Linux?". Bonus: This sounds easy and it is easy!
Yes, take a look here for the hardware specific part:
https://github.com/adafruit/adafruit-beaglebone-io-python/issues/157
It describes fairly well both the new and the old sysfs interfaces you can use to manipulate GPIOs.
Depending on the language of your choice, there may already be bindings or a library to abstract this.
No (only based on the information you provided, are there other requirements?)
We all were new at this at some point, don't worry.
Sidenote: It's generally a good idea to make sure that you are running the latest firmware. In case of the BB-Family you can find them here: http://beagleboard.org/latest-images
Related
I have a piece of software that is designed to work with older SATA hard drives and uses a specific ioctl to obtain information from it. Unfortunately I don't have the sources available so I can't just change it. So I wonder is it somehow possible to man in the middle the ioctl and fill out the information myself? This way I can write a simple tool that uses a different mechanism to get the information the tool expects.
Any help is appreciated
I am currently a student at a university studying a computing related degree and my current project is focusing on finding vulnerabilities in the Linux kernel. My aim is to both statically audit as well as 'fuzz' the kernel (targeting version 3.0) in an attempt to find a vulnerability.
My first question is 'simple' is fuzzing the Linux kernel possible? I have heard of people fuzzing plenty of protocols etc. but never much about kernel modules. I also understand that on a Linux system everything can be seen as a file and as such surely input to the kernel modules should be possible via that interface shouldn't it?
My second question is: which fuzzer would you suggest? As previously stated lots of fuzzers exist that fuzz protocols however I don't see many of these being useful when attacking a kernel module. Obviously there are frameworks such as the Peach fuzzer which allows you to 'create' your own fuzzer from the ground up and are supposedly excellent however I have tried repeatedly to install Peach to no avail and I'm finding it difficult to believe it is suitable given the difficulty I've already experienced just installing it (if anyone knows of any decent installation tutorials please let me know :P).
I would appreciate any information you are able to provide me with this problem. Given the breadth of the topic I have chosen, any idea of a direction is always greatly appreciated. Equally, I would like to ask people to refrain from telling me to start elsewhere. I do understand the size of the task at hand however I will still attempt it regardless (I'm a blue-sky thinker :P A.K.A stubborn as an Ox)
Cheers
A.Smith
I think a good starting point would be to extend Dave Jones's Linux kernel fuzzer, Trinity: http://codemonkey.org.uk/2010/12/15/system-call-fuzzing-continued/ and http://codemonkey.org.uk/2010/11/09/system-call-abuse/
Dave seems to find more bugs whenever he extends that a bit more. The basic idea is to look at the system calls you are fuzzing, and rather than passing in totally random junk, make your fuzzer choose random junk that will at least pass the basic sanity checks in the actual system call code. In other words, you use the kernel source to let your fuzzer get further into the system calls than totally random input would usually go.
"Fuzzing" the kernel is quite a broad way to describe your goals.
From a kernel point of view you can
try to fuzz the system calls
the character- and block-devices in /dev
Not sure what you want to achieve.
Fuzzing the system calls would mean checking out every Linux system call (http://linux.die.net/man/2/syscalls) and try if you can disturb regular work by odd parameter values.
Fuzzing character- or block-drivers would mean trying to send data via the /dev-interfaces in a way which would end up in odd result.
Also you have to differentiate between attempts by an unprivileged user and by root.
My suggestion is narrowing down your attempts to a subset of your proposition. It's just too damn broad.
Good luck -
Alex.
One way to fuzzing is via system call fuzzing.
Essentially the idea is to take the system call, fuzz the input over the entire range of possible values - whether it remain within the specification defined for the system call does not matter.
I have to add a system call in linux kernel that will print the process tree showing only the PIDs to user code. I have to use copy_to_user here. But I am not understanding the use of this function. Could any of u give an example of how it works, including the user-side code and added system code?.....Any easy/simple example would be great for me...:)
Thanks.
I suggest you read through the Linux Device Driver book. It's freely available online at http://lwn.net/Kernel/LDD3/. Although it's geared towards device drivers, it covers most of the key aspects for communicating between kernel and user space and includes multiple examples.
By the way, this sounds like a homework question. If so, your question should have the 'homework' Tag associated with it.
I need some opinions pointers on creating pseudo-filesystems for linux/*nix systems.
Firstly when I say pseudo-filesystem I mean something like /proc where the structure within does not represent actual files on disks or such but the state of the kernel. I would like to try something similar as an interface to an application.
As an example you could say, mount a ftp url to your filesystem and your browser app could then allow you to interact with the remote system doing ls et al on it and translating the standard filesystem requests into ftp ones.
So the first question is: how does one go about doing that? I have read a bit about it and it looks like you need to implement a new kernel module. If possible I would like to avoid that - my thinking being that someone may have already provided a tool for doing this sort of thing and provided the module to assist already.
My second question is: does anyone have a good list of examples of applications/services/whatever using this sort of technique to provide a filesystem based interface.
Lastly if anyone has any opinions on why this might be a good/bad idea to do such a thing on a generic level I would like to hear it.
A userspace filesystem via fuse would probably be your best way to go.
Regarding the next part of your question (which applications use this method), there is the window manager wmii, it uses the 9p filesystem via v9fs, which is a port of 9p to Linux. There are many examples on plan9, most notably acme. I suggested fuse because it seems more actively developed and mainstream in the Linux world, but plan9 is pretty much the reference for this approach as far as I know.
I'm using the RxTx library over usbserial on a Linux distro. The RxTx lib seems to behave quite differently (in a bad way) than how it works over serial.
One of my biggest problems is that the RxTx SerialPortEvent.OUTPUT_BUFFER_EMPTY does not work on linux over usb serial.
How do I know when I should write to the stream? Any indicators I might have missed?
So far my experience with writing and reading concurrently have not been great. Does anyone know if I should lock the DATA_AVAILABLE handler from being invoked while I'm writing on the stream? Or RxTx accepts concurrent read/writes?
(perhaps slightly off-topic, but here goes)
I'm not familiar with that particular library, but I can assure you from dire experience (I work in the security systems (as in: hardware security devices) business, where RS-232 is heavily used) that not all USB-serial converters are born equal. Many such devices so not properly emulate all RS-232 lines, and many don't even handle any comms without flow control. Before blaming the library, try to confirm that the hardware actually does what it's supposed to do.
Without wanting to endorse a particular product or brand, the best (as in: least buggy) USB-serial converter I have come across in years is the USA-19HS.
Using RxTx over usb-to-serial you can't set notifyOnOutput to true otherwise it locks up completely.
I've learned this the hard way. This problem is documented on a few web sites over the internet.
I'm running it on Linux and I believe that this is a Linux only issue, although I can't confirm that.
As for the link you've given me... I've seen the SimpleReader and SimpleWriter examples, but these don't represent a real world application. It is not multi-threaded, assumes a read has the full data it needs instead of buffering reads, etc.
Thanks,
Jeach!